The spatial and temporal expression of Ch-en, the engrailed gene in the polychaete Chaetopterus, does not support a role in body axis segmentation.
The spatial and temporal expression of Ch-en, the engrailed gene in the polychaete Chaetopterus, does not support a role in body axis segmentation.
复制标题
多毛类 Chaetopterus 中的 engrailed 基因 Ch-en 的空间和时间表达不支持在身体轴分割中的作用。
DOI：
10.1006/dbio.2001.0309
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Martindale,MQ
中科院分区：
文献类型：
--
作者：
Seaver,EC;Paulson,DA;Irvine,SQ;Martindale,MQ
我们有兴趣了解是否环节动物和节肢动物共享一个共同的分段祖先，并已接近这个问题，通过表征的片段极性基因engrailed（EN）在基底环节动物，多毛类Chaetopterus的表达模式。我们从毛翅目昆虫cDNA文库中克隆了一个en基因Ch-en。基因组Southern印迹表明，这是唯一的en类基因在这种动物。预测的蛋白质序列的1.2 kb的cDNA克隆包含所有五个结构域的EN蛋白在其他类群，包括EN类同源框的特征。整体原位杂交显示，陈恩在整个幼虫的生活中表达在一个复杂的空间和时间模式。Ch-en转录最初在与顶端器官相关的少数神经元和原担轮体的后部中检测到。在后期阶段，Ch-en在Chaetopterus的三个分节体区域（A，B和C）中以不同的模式表达。在所有节段中，Ch-en在CNS中的一小组节段迭代细胞中表达。在A区，Ch-en也表达于毛囊基部的一小群中胚层细胞中。在B区，Ch-en最初在中胚层中广泛表达，然后分解成与形态学分割一致的一条带/片段。B区域中的中胚层表达位于每个节段的前部区域，如腹神经索中神经节的位置所定义的，并且参与幼虫生命后期的节段特异性摄食结构的形态发生。我们观察到带状中胚层和外胚层染色的前-后序列中的C区。我们没有观察到一段极性模式的陈恩外胚层中的表达，如在节肢动物中观察到的。
We are interested in understanding whether the annelids and arthropods shared a common segmented ancestor and have approached this question by characterizing the expression pattern of the segment polarity gene engrailed (en) in a basal annelid, the polychaete Chaetopterus. We have isolated an en gene, Ch-en, from a Chaetopterus cDNA library. Genomic Southern blotting suggests that this is the only en class gene in this animal. The predicted protein sequence of the 1.2-kb cDNA clone contains all five domains characteristic of en proteins in other taxa, including the en class homeobox. Whole-mount in situ hybridization reveals that Ch-en is expressed throughout larval life in a complex spatial and temporal pattern. The Ch-en transcript is initially detected in a small number of neurons associated with the apical organ and in the posterior portion of the prototrochophore. At later stages, Ch-en is expressed in distinct patterns in the three segmented body regions (A, B, and C) of Chaetopterus. In all segments, Ch-en is expressed in a small set of segmentally iterated cells in the CNS. In the A region, Ch-en is also expressed in a small group of mesodermal cells at the base of the chaetal sacs. In the B region, Ch-en is initially expressed broadly in the mesoderm that then resolves into one band/segment coincident with morphological segmentation. The mesodermal expression in the B region is located in the anterior region of each segment, as defined by the position of ganglia in the ventral nerve cord, and is involved in the morphogenesis of segment-specific feeding structures late in larval life. We observe banded mesodermal and ectodermal staining in an anterior–posterior sequence in the C region. We do not observe a segment polarity pattern of expression of Ch-en in the ectoderm, as is observed in arthropods.